A main concern over the years for detergent manufacturers has been providing detergent compositions which exhibit good solubility in various wash water conditions. This concern has particularly become important in the field recently with the proliferation of higher density "compact" detergents, i.e., detergent compositions having bulk densities of 600 g/l or higher. Poor solubility of a detergent composition may result in, e.g., clumps of detergent which appear as solid white masses remaining in the washing machine and/or on washed clothes. In particular, such clumps can occur in cold wash water conditions and/or when the order of addition to the washing machine is laundry detergent first, clothes second, and water last.
The various approaches detergent manufacturers have taken to improve the solubility of detergent compositions include: (a) compacting spray-dried granules at low pressures (20 to 200 psi) and granulating the resulting compacted material; (b) combining at least two multi-ingredient components, one being spray-dried and containing slower-dissolving detergent surfactant, the other being agglomerated and containing a faster-solubilizing detergent surfactant; and (c) incorporating admixed hydrophobic amorphous silicate material into a sodium carbonate-containing detergent, bleach, or additive composition.
The prior art discloses spraying nonionic surfactant over the surfaces of spray-dried base detergent beads, but fails to disclose the desirability and/or the practicality of combining the incorporation of nonionic into a spray-dried granule while the granule is relatively hot in combination with cooling and mixing steps. It would be desirable to have detergent granules that exhibit improved solubility and are more crisp and free-flowing than the aforementioned prior art granules.
Therefore, despite the aforementioned disclosures in the art, there remains a need for a process which provides a detergent composition having improved solubility. There is also a need for such a process which provides a detergent composition which has improved flow properties in that it is more crisp and free-flowing.